Radiation curable gel inks are advantageous over conventional liquid inks at least because they tend to form drops having less mobility than those formed by conventional inks. Gel inks are deposited onto a substrate in liquid form. The liquid gel ink drops are quickly quenched to a gel state upon contact with the substrate, and have limited mobility.
Conventional inks tend to form mobile liquid drops upon contact with a substrate. As such, substrates are typically coated and/or treated to prevent, for example, coalescence of mobile liquid ink drops. A paper substrate for use with conventional inks may be coated with materials that increase adhesion characteristics and increase surface energy, or otherwise affect chemical interaction between the paper substrate and inks. Such coatings or treatments require special operations for their application to the media, and additional cost is associated with their use. Radiation curable gel inks are desirable at least because they exhibit superior drop positioning on a variety of substrate types, regardless of how the substrates are treated. It is cost advantageous, for example, to run the same media or substrate type across multiple printing apparatuses and not to have to carry, for example, specially coated stock. Further, a printing process using digital presses and conventional presses may require different media supplies suitable for each press.